Reuters: Known oil, gas and coal reserves may already contain a quarter more carbon than mankind can emit and still avoid dangerous climate change, putting the value of new oil exploration in doubt, said a former oil major executive. The oil industry may be wasting $50 billion annually searching for new fields, said Jan-Peter Onstwedder, formerly BP’s most senior risk manager. He left BP (BP.L: Quote, Profile, Research) in December. He calculated potential carbon emissions from proven …